Electromagnetic radiation emitting optoelectronic components have a very broad field of application at present. Within a given application, the color, output and mounting characteristics of such an optoelectronic component will vary widely. It therefore makes sense to provide each optoelectronic component with a housing shape, housing type and/or housing assembly specific to the application. LEDs (light emitting diodes), in particular, also known as light diodes or luminescent diodes, are considered here to be electromagnetic radiation emitting optoelectronic components.
LEDs are being used to an ever-greater extent in floodlights or projection applications. An example of a floodlight in which electromagnetic radiation emitting LEDs are used is described in DE 103 15 131 A1. The device in question is a motor vehicle headlight in which a plurality of semiconductor chips is disposed in a common housing cavity.
White light for floodlight applications is obtained, for example, by chip level conversion. For this purpose, a thin layer of a conversion material is applied to the semiconductor chip right in the production process, thus yielding a white-light chip.
In such floodlight applications, it is desirable for an electromagnetic radiation emitted by the semiconductor chip or chips to be beamed into a predetermined, narrow solid angle with the highest possible radiation density. Since these floodlight applications are steadily gaining influence in the automotive industry, vehicle headlights, especially low beam lamps, are already being made with LEDs today. In this application, LED manufacturers must ensure that the light does not deviate from a desired radiation angle, or that the light intensity outside the preferred radiation angle is sharply attenuated, for example by means of special devices. The underlying consideration here is the specific radiation characteristic that headlights must have in traffic, particularly in order to ensure that oncoming vehicles are not blinded by the arrangement of the headlights. One current solution is the use of optics such as projection lenses to project beam cones onto a desired plane.
A disadvantage of this approach is that in such applications, irregularities in the radiation characteristic of the LED used may be amplified and thus become especially troublesome. In this connection, there is a need for components that are designed specifically for such applications in terms of their radiation properties. Known from Patent Application DE 10 2005 059524 A1 is a housing assembly in which a housing base body having a recess is disposed on at least one chip mounting surface. At least one outer surface of the base body, on the radiation side of the housing and adjacent to the recess, is provided with a screening layer suitable for screening out electromagnetic radiation.
A further disadvantage of the known prior art is that a cover to protect the semiconductor chips and the bonding wiring inside the housing cavity is connected to the housing underpart by an adhesive material. In the edge regions of the housing underpart, this adhesive material forms a bead as a result of the production process. Light is optically coupled into the cover through this bead and leaves it only upon reaching the side surfaces of the cover. The cover functions as a sort of a light guide. Because the cover is not ground to be planar, the incoupled light is refracted every which way by the side surfaces of the cover, resulting in the undesired emission of light, including emission deviating from a preferred emission direction.